package org.david.util {
	/**
	 * @author david
	 */
	import flash.system.Capabilities;

	public class GUID {
		private static var counter : Number = 0;

		public function GUID() {
		}

		public static function create() : String {
			var dt : Date = new Date();
			var id1 : Number = dt.getTime();
			var id2 : Number = Math.random() * Number.MAX_VALUE;
			var id3 : String = flash.system.Capabilities.serverString;
			// System.capabilities.serverString;
			return calculate(id1 + id3 + id2 + counter++).toUpperCase();
		}

		private static function calculate(src : String) : String {
			return hex_sha1(src);
		}

		private static function hex_sha1(src : String) : String {
			return binb2hex(core_sha1(str2binb(src), src.length * 8));
		}

		private static function core_sha1(x : Array, len : Number) : Array {
			x[len >> 5] |= 0x80 << (24 - len % 32);
			x[((len + 64 >> 9) << 4) + 15] = len;
			var w : Array = new Array(80), a : Number = 1732584193;
			var b : Number = -271733879, c : Number = -1732584194;
			var d : Number = 271733878, e : Number = -1009589776;
			for (var i : Number = 0; i < x.length; i += 16) {
				var olda : Number = a, oldb : Number = b;
				var oldc : Number = c, oldd : Number = d, olde : Number = e;
				for (var j : Number = 0; j < 80; j++) {
					if (j < 16)
						w[j] = x[i + j];
					else
						w[j] = rol(w[j - 3] ^ w[j - 8] ^ w[j - 14] ^ w[j - 16], 1);
					var t : Number = safe_add(safe_add(rol(a, 5), sha1_ft(j, b, c, d)), safe_add(safe_add(e, w[j]), sha1_kt(j)));
					e = d;
					d = c;
					c = rol(b, 30);
					b = a;
					a = t;
				}
				a = safe_add(a, olda);
				b = safe_add(b, oldb);
				c = safe_add(c, oldc);
				d = safe_add(d, oldd);
				e = safe_add(e, olde);
			}
			return new Array(a, b, c, d, e);
		}

		private static function sha1_ft(t : Number, b : Number, c : Number, d : Number) : Number {
			if (t < 20)
				return (b & c) | ((~b) & d);
			if (t < 40)
				return b ^ c ^ d;
			if (t < 60)
				return (b & c) | (b & d) | (c & d);
			return b ^ c ^ d;
		}

		private static function sha1_kt(t : Number) : Number {
			return (t < 20) ? 1518500249 : (t < 40) ? 1859775393 : (t < 60) ? -1894007588 : -899497514;
		}

		private static function safe_add(x : Number, y : Number) : Number {
			var lsw : Number = (x & 0xFFFF) + (y & 0xFFFF);
			var msw : Number = (x >> 16) + (y >> 16) + (lsw >> 16);
			return (msw << 16) | (lsw & 0xFFFF);
		}

		private static function rol(num : Number, cnt : Number) : Number {
			return (num << cnt) | (num >>> (32 - cnt));
		}

		private static function str2binb(str : String) : Array {
			var bin : Array = new Array();
			var mask : Number = (1 << 8) - 1;
			for (var i : Number = 0; i < str.length * 8; i += 8) {
				bin[i >> 5] |= (str.charCodeAt(i / 8) & mask) << (24 - i % 32);
			}
			return bin;
		}

		private static function binb2hex(binarray : Array) : String {
			var str : String = new String("");
			var tab : String = new String("0123456789abcdef");
			for (var i : Number = 0; i < binarray.length * 4; i++) {
				str += tab.charAt((binarray[i >> 2] >> ((3 - i % 4) * 8 + 4)) & 0xF) + tab.charAt((binarray[i >> 2] >> ((3 - i % 4) * 8)) & 0xF);
			}
			return str;
		}
	}
}
